Method for patterning a multilayered conductor/substrate structure

ABSTRACT

A method for patterning a multilayered conductor/substrate structure includes the steps of: providing a multilayered conductor/substrate structure which includes a plastic substrate and at least one conductive layer overlying the plastic substrate; and irradiating the multilayered conductor/substrate structure with ultraviolet radiation such that portions of the at least one conductive layer are ablated therefrom. In a preferred embodiment, a projection-type excimer laser system is employed to rapidly and precisely ablate a pattern from a mask into the at least one conductive layer. Preferably, the excimer laser is controlled in consideration of how well the at least one conductive layer absorbs radiation at particular wavelengths. Preferably, a fluence of the excimer laser is controlled in consideration of an ablation threshold level of at least one conductive layer. According to a preferred method, the excimer laser is employed and controlled to ablate portions of the at least one conductive layer without completely decomposing the at least one functional layer therebeneath.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to application Ser. No. 09/783,105 entitled“Multilayered Electrode/Substrate Structures And Display DevicesIncorporating The Same”, filed herewith on Feb. 14. 2001. This patentapplication is assigned to the same assignee as the related application,said related application being incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates generally to laser ablation of conductivefilms and, more specifically, to a method for laser patterning amultilayered conductor/plastic substrate structure and to multilayeredelectrode/plastic substrate structures and display devices incorporatingthe same.

2. Description of the Related Art

A liquid crystal display (LCD) is a type of flat panel display used invarious electronic devices. Generally, LCDs comprise two sheets ofpolarizing material with a liquid crystal solution therebetween. Eachsheet of polarizing material typically comprises a substrate of glass ortransparent plastic; the liquid crystal (LC) is used as opticalswitches. The substrates are usually manufactured with transparentelectrodes, typically made of indium tin oxide (ITO), to whichelectrical “driving” signals are coupled. The driving signals induce anelectric field which can cause a phase change or state change in the LCmaterial; the LC exhibiting different light-reflecting characteristicsaccording to its phase and/or state.

Liquid crystals may be nematic, smectic or cholesteric depending uponthe arrangement of the molecules. A twisted nematic cell is made up of:two bounding plates (usually glass slides), each with a transparentconductive coating (such as ITO) that acts as an electrode, spacers tocontrol the cell gap, two crossed polarizers (the polarizer and theanalyzer), and nematic liquid crystal material. Twisted nematic displaysrotate the director of the liquid crystal by 90°. Super-twisted nematicdisplays employ up to a 270° rotation. This extra rotation gives thecrystal a much steeper voltage-brightness response curve and also widensthe angle at which the display can be viewed before losing muchcontrast. Cholesteric liquid crystal (CLC) displays are normallyreflective (meaning no backlight is needed) and can function without theuse of polarizing films or a color filter. “Cholesteric” means a type ofliquid crystal having finer pitch than that of twisted nematic and supertwisted nematic. Sometimes it is called “chiral nematic” becausecholesteric liquid crystal is normally obtained by adding chiral agentsto host nematic liquid crystals. Cholesteric liquid crystals may be usedto provide bi-stable and multi-stable displays that, due to theirnon-volatile “memory” characteristic, do not require a continuousdriving circuit to maintain a display image, thereby significantlyreducing power consumption. Ferroelectric liquid crystals (FLCs) useliquid crystal substances that have chiral molecules in a smectic C typeof arrangement because the spiral nature of these molecules allows themicrosecond switching response time that make FLCs particularly suitedto advanced displays. Surface-stabilized ferroelectric liquid crystals(SSFLCs) apply controlled pressure through the use of a glass plate,suppressing the spiral of the molecules to make the switching even morerapid.

Some known LCD devices include chemically-etched, transparent,conductive layers overlying a glass substrate. See, e.g., U.S. Pat. No.5,667,853 to Fukuyoshi et al., incorporated herein by reference.Unfortunately, chemical etching processes are often difficult to controlespecially for plastic films. As a consequence, electrodes resultingfrom such processes are often misshaped, with “wells” being formed nearthe substrate in instances where too much etchant was employed.Moreover, the minimum line gaps obtained in plastic films are typicallylimited to 15 μm or more. Additionally, concerns for the environmentlessen the desirability of employing chemical etching processes whichproduce dangerous and/or harmful byproducts.

There are alternative display technologies to LCD's that may be used forexample in flat panel displays. A notable example is organic lightemitting devices (OLEDs), which are comprised of several layers in whichone of the layers is comprised of an organic material that can be madeto electroluminesce by applying a voltage across the device. An OLEDdevice is typically a laminate formed on a substrate such as glass. Alight-emitting layer of a luminescent organic solid, as well as adjacentsemiconductor layers, are sandwiched between an anode and a cathode. Thesemiconductor layers may be hole-injecting and electron-injectinglayers. The light-emitting layers may be selected from any of amultitude of light emitting organic solids, e.g. polymers. When apotential difference is applied across the cathode and anode, electrodesfrom the electrode-injecting layer and holes from the hole-injectinglayer are injected into the light-emitting layer. They recombine,emitting light.

In a typical matrix-addressed light-emitting display device, numerouslight emitting devices are formed on a single substrate and arranged ingroups in a regular grid pattern. Activation may be by rows and columns,or in an active matrix with individual cathode and anode pads. OLED'sare often manufactured by first depositing a transparent electrode onthe substrate, and patterning the same into electrode portions. Theorganic layer(s) is then deposited over the transparent electrodes. Ametallic electrode may be formed over the electrode layers. For example,in U.S. Pat. No. 5,703,436 to Forrest et al., incorporated herein byreference, transparent indium tin oxide (ITO) is used as thehole-injecting electrode, and a Mg-Ag-ITO electrode layer is used forelectron injection.

An excimer laser has been employed to pattern ITO electrode materialoverlying a glass or quartz substrate. See, e.g., U.S. Pat. No.4,970,366 to Imatou et al. and European Patent Specification EP 0 699375 B1 by Philips Electronics N.V., both incorporated herein byreference. However, electrode/substrate structures formed with glass orquartz substrates lack the flexibility and thickness desired for manydisplay products.

F. E. Doany et al., “Large-field scanning laser ablation system”, IBMJournal of Research and Development, Vol. 41, No. ½, 1997, incorporatedherein by reference, discloses a large-field scanning laser ablationsystem which employs a XeCl 308 nm excimer laser and a mask for ablatingvias (down to 8 μm) in a polyimide layer. The system employs aprojection lens (Dyson-type) to image a portion of a full-field maskonto a portion of the substrate. The system also includes a lighttunnel/homogenizer which outputs a square beam with uniformity of ±5%across the entire output field, producing an 8-mm×8-mm illumination spotat approximately 0.05 NA.

Excimer lasers have also been used to manufacture thin-film transistors(TFTs). For example, “Flat-Panel Displays Slim Down with Plastic”,Science and Technology Review, Nov. 1999, incorporated herein byreference, discloses using an excimer laser to manufacture TFTs on topof thin, plastic sheets. In this reference, an amorphous silicon dioxidelayer acts as a thermal barrier to prevent the plastic (PET) substratefrom heating and melting. See also, U.S. Pat. No. 5,714,404 to Mitlitskyet al. and U.S. Pat. Nos. 5,817,550 and 5,856,858 to Carey et al., bothincorporated herein by reference, which disclose using an excimer laserfor crystallizing a TFT silicon layer and for doping.

It is also known to employ an infra-red (IR) fiber laser for patterninga metallic conductive layer overlying a plastic film, directly ablatingthe conductive layer by scanning a pattern over the conductor/filmstructure. See: Int. Publ. No. WO 99/36261 by Polaroid Corporation; andChu et al., “42.2: A New Conductor Structure for Plastic LCDApplications Utilizing ‘All Dry’ Digital Laser Patterning,” 1998 SIDInternational Symposium Digest of Technical Papers, Anaheim, Calif., May17-22, 1998, no. VOL. 29, May 17, 1998, pages 1099-1101, bothincorporated herein by reference. However, metallic conductive layersformed from silver-based, transparent, conductor materials arerelatively expensive. Moreover, employing the aforementioned directlasering techniques is relatively slow and requires complex lasercontrol mechanisms and algorithms to control and direct the narrow IRlaser beam.

Accordingly, a high-speed, high-precision, chemical-free method forpatterning conductor/plastic substrate structures is needed. To thisend, it would also be desirable to have available a flexibleconductor/plastic substrate structure with a “glass replacement”structure which includes material insulating the glass replacementstructure from heat generated during laser irradiation of theconductor/substrate structure. A method for patterningconductor/substrate structures which is sufficiently fast to accommodatea roll-to-roll manufacturing process “downstream” of the patterningprocess would also be useful and potentially yield cost savings in themanufacturing of LCD devices.

SUMMARY OF THE INVENTION

The present invention is embodied in laser-etched multilayeredelectrode/substrate structures and methods for manufacturing the same.In a preferred embodiment, a projection-type excimer laser system isemployed to rapidly and precisely ablate a pattern from a mask into atleast one conductive layer of a multilayered conductor/plastic substratestructure.

In a preferred embodiment, the multilayered conductor/plastic substratestructure includes a “protective layer” which creates a “controlledenvironment” for the laser etching process. The protective layer (e.g.,hard coat) serves to protect layers beneath the protective layer fromdamage caused by laser irradiation of the multilayered electrode/plasticsubstrate structure. This layer facilitates and speeds the laser etchingprocess. Advantageously, this “protective layer” is a functional layerof a “glass replacement” composite, as discussed below.

In a preferred embodiment, the multilayered conductor/plastic substratestructure incorporates one or more functional layers therein. The one ormore functional layers of multilayered electrode/plastic substratestructure serve to insulate, promote adhesion, protect layers underneathfrom laser irradiation, provide protection from environmental damage,and/or provide protection from structural damage, for example, scratchesor cracks in the film.

In a preferred embodiment, the at least one functional layer includes a“barrier layer” (e.g., SiO_(x)) which provides “environmentalprotection” for the plastic substrate. “Environmental protection” meansserving to provide barrier properties against oxygen and/or moisture.

The plastic substrate as constructed with the one or more functionallayers can be seen as a “glass replacement” structure, in that variousproperties of the structure are intended to duplicate variouscharacteristics of the glass substrate, such as the aforementionedbarrier properties. The glass replacement structure can be a compositeof these layers (“glass replacement” composite), or a single layer wherethe functional properties are incorporated through, for example,compounding or coextrusion of the plastic substrate (“glass replacement”layer).

A multilayered electrode/substrate structure in accordance with oneembodiment of the present invention includes: a plastic substrate; andat least one conductive layer overlying the plastic substrate, the atleast one conductive layer being excimer laser-etched into a pluralityof discrete conductive elements. In a preferred embodiment, the at leastone conductive layer includes an ITO layer which is polycrystalline. Ina preferred embodiment, the at least one functional layer serves to:electrically insulate the discrete conductive elements; promote adhesionof the at least one conductive layer to the plastic substrate; protectthe plastic substrate from laser irradiation; protect one or more otherfunctional layers including a barrier layer from laser irradiation;protect the plastic substrate from environmental damage caused byexposure to oxygen and/or moisture; or a combination of the above.

A multilayered electrode/substrate structure in accordance with anotherembodiment of the present invention includes: a plastic substrate; atleast one conductive layer overlying the plastic substrate; and at leastone functional layer intermediate the plastic substrate and the at leastone conductive layer, the at least one functional layer including aninsulating material; wherein portions of the at least one conductivelayer are excimer laser etched. In a preferred embodiment, the at leastone conductive layer includes an ITO layer which is polycrystalline. Ina preferred embodiment, the at least one functional layer includes aprotective layer which serves to protect layers beneath the protectivelayer from laser irradiation. In a preferred embodiment, portions of theprotective layer underlying the etched portions of the at least oneconductive layer are not completely decomposed. In a preferredembodiment, the at least one functional layer includes one or morebarrier layer which serves to protect the plastic substrate fromenvironmental damage. In a preferred embodiment, the multilayeredelectrode/substrate structure further includes an additional functionallayer abutting a side of the plastic substrate that faces away from theat least one conductive layer, the additional functional layer servingto provide structural protection and/or environmental protection for theplastic substrate.

A multilayered electrode/substrate structure in accordance with anotherembodiment of the present invention includes: a substrate; a layer ofindium tin oxide (ITO) which is polycrystalline; and at least onefunctional layer, at least one of which serves as an adhesion promoterof the ITO layer to the substrate; wherein portions of the ITO layer areexcimer laser etched. In a preferred embodiment, the at least onefunctional layer includes a protective layer which serves to protectlayers beneath the protective layer from laser irradiation. In apreferred embodiment, portions of the protective layer underlying theetched portions of the at least one conductive layer are not completelydecomposed. In a preferred embodiment, the at least one functional layerincludes a barrier layer which serves to protect the plastic substratefrom environmental damage. In a preferred embodiment, the multilayeredelectrode/substrate structure further includes an additional functionallayer abutting a side of the plastic substrate that faces away from theat least one conductive layer, the additional functional layer servingto provide structural protection and/or environmental protection for theplastic substrate.

A liquid crystal display device in accordance with another embodiment ofthe present invention incorporates any of the multilayeredelectrode/substrate structures described herein.

A method for patterning a multilayered conductor/substrate structure inaccordance with another embodiment of the present invention includes thesteps of: providing a multilayered conductor/substrate structure whichincludes a plastic substrate and at least one conductive layer overlyingthe plastic substrate; and irradiating the multilayeredconductor/substrate structure with ultraviolet radiation such thatportions of the at least one conductive layer are removed therefrom suchas through ablation. Preferably, the ultraviolet radiation is spatiallyincoherent. According to a preferred method, the irradiating stepincludes employing an excimer laser to ablate portions of the at leastone conductive layer. Preferably, the excimer laser is part of aprojection-type ablation system which is configured to project abroadened laser beam. Preferably, the excimer laser is controlled inconsideration of how well the at least one conductive layer absorbsradiation at particular wavelengths. Preferably, the excimer laser iscontrolled to image a pattern from a mask onto the at least oneconductive layer. Preferably, a fluence of the excimer laser iscontrolled in consideration of an ablation threshold level of the atleast one conductive layer. According to a preferred method, the excimerlaser is employed and controlled to ablate portions of the at least oneconductive layer without completely decomposing the layer therebeneath.In a preferred embodiment, the layer therebeneath is one or morefunctional layers.

The above described and many other features and attendant advantages ofthe present invention will become apparent as the invention becomesbetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed description of preferred embodiments of the invention will bemade with reference to the accompanying drawings:

FIG. 1 is a plot of the transmission rate as a function of wavelengthfor a film with a conductive layer of ITO;

FIG. 2 is a plot of the absorption rate as a function of wavelength fora film with a conductive layer of ITO;

FIG. 3 is a plot of the absorption rate as a function of wavelength fora film with a conductive layer comprising an Au/Ag/Au layer and an ITOlayer formed thereover;

FIG. 4 is a cross-sectional view of an exemplary preferredconductor/plastic substrate structure according to the presentinvention;

FIG. 5 is a cross-sectional view of another exemplary preferredconductor/plastic substrate structure according to the presentinvention;

FIG. 6A is a partial top view of an etched conductor/plastic substratestructure;

FIG. 6B is an enlarged view of portion of the conductor/plasticsubstrate structure of FIG. 6A;

FIG. 6C is a cross-sectional side view of the conductor/plasticsubstrate structure of FIG. 6B;

FIG. 6D is an atomic force microscope image which shows a line ablatedinto a multilayered conductor/substrate structure according to thepresent invention;

FIG. 6E is a section analysis showing the clean, substantiallyrectangular cross-section of the line or groove ablated into themultilayered conductor/substrate structure of FIG. 6D.

FIG. 7 is a top view of an exemplary electrode/substrate structureaccording to the present invention;

FIG. 8 shows excimer laser irradiation of a conductor/substratestructure;

FIG. 9 conceptually illustrates how the method of the present inventioncan, in some circumstances, employ an assist mechanism whereby theprotective layer swells to assist in the removal of the at least oneconductive layer during the ablation process;

FIG. 10 is a cross-sectional view of an exemplary preferred fastmultistable liquid crystal displays (FMLCD) cell structure according tothe present invention;

FIGS. 11-13 illustrate back and front panel processing and panel matingaccording to the present invention;

FIG. 14 is a schematic of an exemplary preferred ablation systemaccording to the present invention; and

FIG. 15 conceptually illustrates a serpentine scan pattern for analternative ablation system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following is a detailed description of the best presently known modeof carrying out the invention. This description is not to be taken in alimiting sense, but is made merely for the purpose of illustrating thegeneral principles of the invention.

The present invention exploits a critical relationship between thewavelength of laser light and the absorption characteristics of theconductor layer. Knowledge of this relationship facilitates precisecontrol of internal film behavior during the patterning process.

Referring to FIG. 1, the transmission rate as a function of wavelengthfor a film with a conductive layer of ITO is shown. The ITO is verytransparent to infra-red light. The transmission rates shown in FIG. 1make the use of IR (mean IR) lasers impractical for high-speedpatterning of this kind of conductive layer due to the very low etchrates achievable. Moreover, high power IR lasers are needed for low tomedium speeds.

As seen in FIG. 2, this film has much higher absorption rates at UVlight wavelengths (<350 nm), for example, ˜3.5% at 308 nm. Therefore, UVlasers are more suited for this film given that the very high power IRlasers need for ablating ITO produce high amounts of heat which canquickly damage the plastic layers of the film.

Among the UV lasers, the preferred laser for implementing the presentinvention is an excimer laser because of its powerful outputs andbecause excimer lasers are readily used in lithography systems employingmasks. This is possible because of the high exposure power and thespatial incoherence of excimer lasers which make wafer exposure timesshorter than with other UV lights. The choice of an excimer laser isparticularly preferred when the substrate is plastic in order to lessenthe amount of heat generated by the laser and conducted to the plasticlayer(s). The spatial incoherence of excimer lasers (in contrast withother widely used lasers) makes speckles much less likely. Speckles(interference patterns) make high resolution imaging rather impractical.Transparent conductive materials are widely made of transparentconductive oxide films having optical energy gaps of 3 to 4 eV and arenot effectively processed by IR lasers (of photon energies of around 1.5eV). The wavelength of the excimer laser is no longer than 400 nmequivalent to photon energies higher than 3.1 eV. Excimer lasers alsohave a very short pulse width delivering their energy in nanoseconds.

FIG. 3 shows the absorption rate as a function of wavelength for a filmwith a conductive layer comprising an Au/Ag/Au layer and an ITO layerformed thereover, illustrating how the selection of different materialsfor the conductor/plastic substrate structure results in differentabsorption characteristics. For example, the absorption rate for thisfilm is ˜1.0-1.5% at 308 nm. At IR wavelengths, this film exhibitssomewhat higher absorption than the film of FIG. 2 because of theAu/Ag/Au layer.

Referring to FIG. 4, an exemplary preferred conductor/plastic substratestructure 400 according to the present invention comprises at least oneconductive layer 402 and a multilayer structure 404 which functions as a“glass replacement” composite. The at least one conductive layer 402 ispreferably formed from material(s) selected to satisfy the followingthree criteria: high transparency (at least 80% transmission at visiblelight wavelengths), low resistivity (1-80Ω/square), and environmentalstability. Another important criteria of the at least one conductivelayer 402 is flexibility to prevent cracking of electrodes fromroll-to-roll processing. The at least one conductive layer 402comprises, for example, an oxide layer (e.g., ITO), a metal-based layer(e.g., silver-based, palladium-based), an alloy layer (e.g., ITO alloy,silver alloy), a doped layer (e.g., ITO doped with cerium oxide), amultilayered conductive film (e.g., Au/Ag/Au), or a combination of theabove.

Indium tin oxide (ITO) is a cost effective conductor with goodenvironmental stability, up to 90% transmission, and down to 20Ω/squareresistivity. An exemplary preferred ITO layer 402 has a % T≧80% in thevisible region of light (>400 nm to 700 nm) so that the film will beuseful for display applications. In a preferred embodiment, the at leastone conductive layer 402 comprises a layer of low temperature ITO whichis polycrystalline. The ITO layer is preferably 10-120 nm in thickness,or 50-100 nm thick to achieve a resistivity of 20-60 Ω/square onplastic. An exemplary preferred ITO layer is 60-80 nm thick.

The at least one conductive layer 402 can comprise other metal oxidessuch as indium oxide, titanium dioxide, cadmium oxide, gallium indiumoxide, niobium pentoxide and tin dioxide. See, Int. Publ. No. WO99/36261 by Polaroid Corporation. In addition to a primary oxide such asITO, the at least one conductive layer 402 can also comprise a secondarymetal oxide such as an oxide of cerium, titanium, zirconium, hafniumand/or tantalum. See, U.S. Pat. No. 5,667,853 to Fukuyoshi et al. Othertransparent conductive oxides include, but are not limited to: ZnO₂,Zn₂SnO₄, Cd₂SnO₄, Zn₂In₂O₅, MgIn₂O₄, Ga₂O₃-In₂O₃, Ta O₃, etc. The atleast one conductive layer 402 is formed, for example, by a (lowtemperature) sputtering technique or by a direct current sputteringtechnique (DC-sputtering or RF-DC sputtering) depending upon thematerial(s) of the underlying layer.

For higher conductivities, the at least one conductive layer 402comprises a silver-based layer which contains silver only or silvercontaining a different element such as aluminum (Al), copper (Cu),nickel (Ni), cadmium (Cd), gold (Au), zinc (Zn), magnesium (Mg), tin(Sn), indium (In), tantalum (ta), titanium (Ti), zirconium (Zr), cerium(Ce), silicon (Si), lead (Pb) or palladium (Pd). See, U.S. Pat. No.5,667,853 to Fukuyoshi et al. In a preferred embodiment, the at leastone conductive layer 402 comprises at least one of gold, silver and agold/silver alloy, for example, a layer of silver coated on one or bothsides with a thinner layer of gold. See, Int. Publ. No. WO 99/36261 byPolaroid Corporation. These higher conductivity conductor structures areformed, for example, employing a direct sputtering technique.

The elements aluminum (Al), copper (Cu), nickel (Ni), cadmium (Cd), gold(Au), zinc (Zn), magnesium (Mg), tin (Sn), indium (In), tantalum (ta),titanium (Ti), zirconium (Zr), cerium (Ce), silicon (Si), lead (Pb) orpalladium (Pd) can also be used in other conductive elements or alloysto form the conductive layer 402.

The “glass replacement” structure 404 comprises a substrate 406 and atleast one “functional layer” intermediate the at least one conductivelayer 402 and the substrate 406. In the exemplary preferred embodimentshown in FIG. 4, the at least one functional layer comprises aprotective layer 408 and a barrier layer 410. The protective layer 408(e.g., acrylic hard coat) functions to prevent laser light frompenetrating to functional layers intermediate the protective layer 408and the substrate 406, thereby protecting—in the illustrated exemplarypreferred embodiment—both the barrier layer 410 and the substrate 406.An exemplary preferred protective layer 408 also serves as an adhesionpromoter of the at least one conductive layer 402 to the substrate 406.

The barrier layer 410 (e.g., SiO_(x), AlO_(x), ITO) is preferablyinorganic and functions to protect layers underneath from environmentaldamage caused by exposure to oxygen and/or water, etc. and acts as anadhesion promoter. The barrier layer 410 protects, for example, againstthe presence of moisture in the LC cell which may lead to the formationof black spots. As the LCD cell gap shrinks, the requirement in barrierperformance increases because fewer water molecules are needed to form avisible black spot. It is believed that the outer barrier layer—i.e. thelayer that protects the LCD cell from the environment—works with theinner barier layer to prevent void formation in the film. These voidsare manifested as black spots. Without the outer barrier layer, heat andrelative humidity is believed to cause film deformation and moistureincursion, contributing to void formation. It has been observed thatSiO^(x) barrier layers are effective in countering this phenomenon. Anexemplary preferred barrier layer 410 acts as a gas barrier (e.g., withan oxygen transmission rate (OTR) no greater than 0.1 cc/m²/day). Asbetween SiO_(x), AlO_(x) and ITO, it has been observed that OTRdecreases in the order: AlO_(x)>ITO>SiO_(x). Another exemplary preferredbarrier layer 410 acts as a moisture barrier (e.g., with a water vaportransmission rate (WVTR) no greater than 0.1 g/m²/day). As betweenSiO_(x), AlO_(x) and ITO, it has been observed that WVTR decreases inthe order: AlO_(x)>SiO_(x)>ITO. Although the protective layer 408 isshown in FIG. 4 overlying the barrier layer 410, alternatively theselayers can by provided with the barrier layer 410 overlying theprotective layer 408.

An exemplary preferred substrate 406 comprises a visiblelight-transmitting material, preferably a flexible material such asplastic or a plastic film. “Plastic” means a high polymer, usually madefrom polymeric synthetic resins, which may be combined with otheringredients, such as curatives, fillers, reinforcing agents, colorants,and plasticizers. A “resin” is a synthetic or naturally occurringpolymer. Plastic is solid in its finished state, and at some stageduring its manufacture or processing into finished articles, can beshaped by flow. Plastic includes thermoplastic materials andthermosetting materials.

An exemplary preferred substrate 406 comprises heat-stabilizedpolyethylene terephthalate (HS-PET). However, other appropriate plasticsubstrates can be used, such as polyethylenenapthalate (PEN),polycarbonate (PC), polyarylate (PAR), polyetherimide (PEI),polyethersulphone (PES), polyimide (PI), Teflonpoly(perfluoro-alboxy)fluoropolymer (PFA), poly(ether ether ketone)(PEEK), poly(ether ketone) (PEK), poly(ethylenetetrafluoroethylene)fluoropolymer (PETFE), and poly(methyl methacrylate)and various acrylate/methacrylate copolymers (PMMA). Certain of theseplastic substrates can withstand higher processing temperatures of up toat least about 200° C. (some to 300°-350° C.) without damage. Variouscyclic polyolefins—for example, ARTON made by JSR Corporation, Zeonormade by Zeon Chemicals L.P., and Topas made by Celanese AG—are alsosuitable for the substrate 406. Other low-temperature plastic substrates(both flexible and rigid) can also be used, including:ethylene-chlorotrifluoro ethylene (E-CTFE), made under the trademarkHALAR by Ausimont U.S.A., Inc., ethylene-tetra-fluoroethylene (E-TFE)made under the trademark TEFZEL by Dupont Corporation,poly-tetrafluoro-ethylene (PTFE), fiber glass enhanced plastic (FEP),and high density polyethylene (HDPE). Although various examples ofplastic substrates are set forth above, it should be appreciated thatthe substrate 406 can also be formed from other materials such as glassand quartz.

In an exemplary preferred application as the core of a FMLCD film, thesubstrate 406 (for example, 200 μm in thickness) is by far the thickestlayer of the film construction. Consequently, the substrate determinesto a large extent the mechanical and thermal stability of the fullystructured FMLCD film. An exemplary preferred substrate 406, therefore,is formed from a material which is stable at 135° C. for 6 hours,resistant to 1″ mandrel cracking, and >2H pencil hardness.

Referring to FIGS. 4 and 5, elements with like numerals are the sameunless otherwise noted. In FIG. 5, another exemplary preferredconductor/plastic substrate structure 400′ according to the presentinvention comprises at least one conductive layer 402 and an alternative“glass replacement” structure 404′ which additionally serves to providethe underside of the substrate 406 with structural protection (e.g.,scratch and drop resistance) and/or environmental protection. Thealternative “glass replacement” structure 404′ is provided with at leastone “functional layer” overlying the substrate 406 and at least oneadditional “functional layer” underlying the substrate 406. In theillustrate exemplary preferred embodiment, two protective layers 408 areprovided adjacent the upper surface and the lower surface of thesubstrate 406, respectively. The illustrated alternative “glassreplacement” structure 404′ also includes a barrier layer 410 underlyingthe lower protective layer 408. It should be appreciated thatcombinations and arrangements of protective layers 408, barrier layers410 and other functional layers different from those shown in FIGS. 4and 5 are also within the scope of the present invention.

The illustrated exemplary preferred “glass replacement” structures 404,404′ include specific, functional layers intermediate the at least oneconductive layer 402 and the substrate 406 and/or on the other side ofthe substrate 406 as described above. However, an integrally-formed“glass replacement” structure (i.e., without specific functional layers)is also within the scope of the present invention. Such a structureencompasses one or more of the functionalities of the above-describedfunctional coatings and, in a preferred embodiment, provides gas and/ormoisture barriers, adhesion to inorganic conductive coatings, scratchresistance, and the environmental stability of glass.

An exemplary preferred method for patterning a multilayeredconductor/substrate structure according to the present inventionincludes the steps of: providing a multilayered conductor/substratestructure 400 (as described above); and irradiating the multilayeredconductor/substrate structure 400 with ultraviolet radiation such thatportions of the at least one conductive layer 402 are ablated therefrom.Referring to FIG. 6A, which shows a partial view of a visible region ofa display device, a conductor/substrate structure 400 is shown with itsat least one conductive layer 402 patterned into a plurality ofelectrodes 412. In the illustrated exemplary preferred embodiment, theelectrodes 412 are parallel. Two conductor/substrate structures 400 sopatterned can be used to form a LCD device. For example, two suchsubstrates 400 are positioned facing each other and cholesteric liquidcrystals are positioned therebetween to form a FMLCD device.

Referring to FIGS. 6B and 6C, illustrative dimensions for a patternedITO conductive layer 402 are: line widths (W_(L)) of 10 microns;distances between lines (i.e. electrode widths) (W_(L-L)) of 200microns; depth of cut (i.e. thickness of ITO conductor) (H) of 100nanometers. ITO thicknesses on the order of 60, 70, and greater than 100nanometers are also possible. For FMLCD applications, the “line gap” ispreferably less than 4 times the “cell gap”. If the line width exceedsthis ×4 value, the driving voltage requirements increase to unacceptablelevels (60, 70, 100 volts). A target line width of 10 microns provides asafe margin of error for the cell geometry.

FIG. 6D is an atomic force microscope image which shows a line ablatedinto a multilayered conductor/substrate structure according to thepresent invention. The film under test comprised, from bottom to top, aPET substrate (175 μm), a SiO_(x) layer, an acrylic hard coat (˜1 μm),and an ITO layer (˜115 nm). The line was ablated employing a XeClexcimer laser at 308 nm wavelength, frequency 50 Hz (rep rate), at afluence of 183 mJ/cm². The section analysis presented in FIG. 6E shows aclean, substantially rectangular cross-section of the line (or groove)ablated into the multilayered conductor/substrate structure of FIG. 6D.

According to an exemplary preferred method of the present invention, anexcimer laser is employed to ablate portions of the at least oneconductive layer 402 to form an electrode/substrate structure. In FIG.7, an exemplary electrode/substrate structure 700 with discreteconductive elements 702 is shown. It should be understood that a greatmany differently patterned electrode/substrate structures can be formedemploying the principles of the present invention.

FIG. 8 shows excimer laser irradiation of the conductor/substratestructure 400 with a beam 800. The excimer laser is controlled inconsideration of how well the at least one conductive layer 402 absorbsradiation at particular wavelengths. Preferably, the excimer laser iscontrolled to image a pattern from a mask onto the at least oneconductive layer 402.

According to the present invention, characteristics of the beam 800 aredefined by: parameters relative to the delivery of exposure dose(average power, pulse energy, repetition rate, pulse width); parametersrelative to the temporal coherence of the laser (spectral bandwidth);and parameters relative to the spatial coherence of the laser (beamdimensions, beam divergence, beam uniformity). In an exemplary preferredembodiment, a laser is employed which provides a range of energy perpulse of 50-1,000 mJ/cm², spectrally narrowed laser wavelengths with thedifference between longer and shorter wavelengths being 0.003 nm, largebeam dimensions (e.g., 7 mm×7 mm (˜50 mm²) broadened laser beam), andbeam uniformity better than 2%. Depending upon the material(s) fromwhich the at least one conductive layer 402 is formed, the fluence(e.g., 180 mJ/cm²) and/or number of pulses (e.g., one pulse, two pulses,etc.) is controlled to ablate a desired amount of material from theconductor/substrate structure 400.

When the at least one conductive layer 402 comprises ITO, the beam 800preferably comprises (spatially incoherent) UV radiation with a discretecharacteristic wavelength of 308 nm or 248 nm. It should be appreciated,however, that the principles of the present invention are not limited tothese particular wavelengths. An exemplary preferred light source forpatterning ITO comprises a medium UV excimer laser. An exemplarypreferred UV light sources is a XeCl (308 nm) excimer laser. This lightsource is generally preferable to a KrF (248 nm) excimer laser becauseof the availability of advanced industrial XeCl lasers and because HClgas is easier to handle than F₂ for KrF lasers. Also, the longerwavelengths of UV light are more suitable to optics than the shorterwavelengths. It should be appreciated, however, that the presentinvention is not limited to employing medium UV light sources,particularly when the material(s) of the at least one conductive layer402 have good absorption characteristics in other regions of theelectromagnetic spectrum. Thus, the principles of the present inventionare also applicable to conductive materials yet to be discovered and/ordeveloped, as well as to materials which are not yet publicly known orknown to be suitable for rendering into conductive materials forconductor/substrate structures.

In one embodiment of the present invention, the protective layer 408comprises a material (such as acrylic) which expands when heated undercertain circumstances. In this embodiment, the material(s) from whichthe at least one conductive layer 402 is formed are carefully selected,and the process of irradiating the at least one conductive layer 402 isprecisely controlled such that the irradiated portion of the at leastone conductive layer 402 is heated and cracked and a portion of theunderlying protective layer 408 swells (as conceptually illustrated inFIG. 9) due primarily to energy thermally conducted through the at leastone conductive layer 402, rather than light transmitted through the atleast one conductive layer 402 to the protective layer 408. As discussedbelow in greater detail, ablation processes can be tailored tofacilitate controlled swelling of the underlying protective layer 408which can help or “assist” the at least one conductive layer 402 to beetched away with greater speed and precision.

Referring to FIG. 9, this cross-sectional view of an etched line showsthat portions of the protective layer 408 underlying the etched portionsof the at least one conductive layer 402 are not completely decomposed.The amount of decomposition and degree of swelling are controlled byprecisely tuning the fluence of the laser in consideration of thematerial(s) from which the at least one conductive layer 402 and theprotective layer 408 are formed and their respective thicknesses. Insome circumstances, the material(s) from which the substrate 406 isformed are also taken into consideration in determining how the laser isto be employed and controlled and/or the substrate 406 also contributesto the “assist” mechanism.

In an exemplary preferred embodiment of the present invention, only aminor part of the protective layer 408 is damaged during the patterningprocess. Thus, the protective layer 408 in such an embodiment iselectrically insulative to prevent shorts between the discreteconductive elements formed by the patterning process.

When the at least one conductive layer 402 is ITO, part of the energy isabsorbed by the hardcoat (acrylic) protective layer 408, even though theITO conductive layer 402 does not pass much of the laser light. Acryliccan only sustain temperatures up to around 200° C., whereas the meltingtemperature of ITO is much higher. At temperatures in the range of200-250° C., acrylic decomposes. Acrylic, like other (organic) polymers,has relatively low thermal conductivity. Therefore, lateral damage isminimized.

The ITO conductive layer 402 has a very low transmittance at thewavelength of 308 nm (and less at 248 nm). Therefore, only a negligiblepercentage of the light is transmitted through the ITO conductive layer402 to the acrylic protective layer 408. Rather, the acrylic is heatedby conducted thermal energy from the ITO conductive layer 402. Theamount of swelling depends upon the level of energy transferred to theprotective layer 408 (which depends upon the thermal conductivity of theat least one conductive layer 402), the composition of the protectivelayer 408, and the glassification temperature (Tg) of the protectivelayer 408. Because of the low thermal conductivity of acrylic, theportion of the protective layer 408 which is close to the ITO conductivelayer 402 heats and swells pushing up the portion of the ITO conductivelayer 402 on top (which is now very much heated) out of the layer 402.This phenomenon helps increase the etching speed and enhance theprecision of the cut with very well defined edges.

Thus, in the embodiment described above, an excimer laser is employed toindirectly heat the acrylic protective layer 408 adjacent the ITOconductive layer 402 causing the acrylic protective layer 408 to swelland push the ITO out of the groove. This swelling mechanism has beenobserved where “large exposure areas” (typically 50 μm wide or more)have been exposed for ITO removal. Remaining portions of the acrylicprotective layer 408 constitute a functional part of the film ashardcoat. The ablation mechanism observed for ITO is discussed below ingreater detail.

Different films were irradiated under excimer laser radiation of 308 nmand fluences in the range of 90 to 230 mJ/cm2, and it was observed thatthe size of the particles generated from the ITO removal appears to beinversely related to the energy levels of the excimer laser. The ITO wasremoved in the form of large particles at lower laser fluences andgradually by increasing the fluence the debris became smaller andsmaller.

Also it was observed that at the laser wavelength of 308 nm there doesnot appear to be a direct relation between the energy level of the laserbeam and the depth of the grooves. Although the lines are much cleaner(no ITO large particles) at higher energies and significantly moreuniform over all of their length, the grooves are not deeper thangrooves (with properly removed particles) formed employing mid-energylevels.

The protective layer underneath the ITO does not play a primordial rolein the removal of the ITO layer until the heat generated in the lowerITO layers is enough to thermally decompose and swell the underneathpolymer layer. This can only happen at levels of energy equal to orgreater than the ablation threshold level (at which there is completeremoval of ITO for a given film).

It is believed that the major mechanism to which the observed resultscan be attributed obeys a photo-thermal model. The absorbed photonenergy results in thermally activated fragmentation of the material andis rapidly converted into the kinetic energy of the rejected particles.It is believed that the formation of small debris at higher energylevels originates from the ablation of the upper layers of the ITO filmwhere the high (laser induced) temperature causes rapid mechanicalscission of the layer. These ejected fragments are then involved incollisional processes in the ablation plume. When material removal issufficiently high, an increased number of collisions occurs resulting inthe small size debris. Only the layers of ITO where this activatedfragmentation is sufficiently high can participate in the process. Therapid conversion of the energies leaves the lower layers at lowtemperature and therefore almost intact.

In contrast with the above, the high mass fragments at mid-energy levelsare believed to originate from lower layers of the ITO where the hightemperatures cause the same mechanical scission of the ITO layer.However, the large fragments are ejected at lower speeds. The smallerablation plume expansion at these fluences does not involve the ejectedmaterial in an intense collisional process; therefore, these fragmentsresult in large size debris. This mechanism also explains why there isno observed direct relation between the increase in the laser energylevel and the measured depth of the grooves formed by the ablationprocess. At the low to mid fluences, the absorbed photon energy whichresults in thermally activated fragmentation of the material is not highenough to completely and rapidly convert into kinetic energy. Therefore,the heat is conducted into the lower layers of the ITO resulting indispersed fragmentation and large particle formation. The converted(into kinetic energy) part of the thermal energy pushes the particle up.These large debris are often re-deposited near the grooves or even stayinside the grooves due to insufficient kinetic energy, but such groovescan be deeper than with the higher energies because deeper layers of theITO have been involved in the process.

The processes described herein are suitable for high-speed ablation ofITO or other conductive layers for patterning electrical circuitry on aconductive layer on top of a plastic (polymer) film construction for usein the display industry. Possible display industry applications include,but are not limited to: ultralight, flexible, and inexpensive displaysfor notebook and desktop computers, instrument panels, video gamemachines, videophones, mobile phones, hand-held PCs, PDAs, e-books,camcorders, satellite navigation systems, store and supermarket pricingsystems, highway signs, informational displays, smart cards, toys, andother electronic devices.

The principles of the present invention are applicable to laserengraving substrates (plastic substrates, in particular) for use in zerofield multistable cholesteric liquid crystal displays. These substratescan contain a conductive matrix that provides a path for a drive voltageto be conveyed to the contained CLCs. The conductive matrix definespixel locations of the liquid crystals contained by these substrates.For zero field multistable displays which do not require polarizers,analyzers, color filters or backlighting components, their resultingthinness makes them particularly well suited for construction oflarge-sized displays with overlapping display segments withoutdistortion of the spatial integrity of the image. See, e.g. U.S. Pat.No. 5,889,566 to Wu et al., incorporated herein by reference. Full-colorcapability can be achieved, for example, by alternately filling channelsinscribed in the substrate with cholesteric liquid crystals havingwavelength maxima reflections in the red, green and blue (RGB) regionsof the visible spectrum. Full-color capability can also be achieved byoverlapping of RGB layers. Although a preferred application involveszero field multistable cholesteric liquid crystal displays, it should beunderstood that the principles of the present invention are alsoapplicable to other types of liquid crystal displays as well as organiclight emitting devices (OLEDs).

Referring to FIG. 10, an exemplary preferred fast multistable liquidcrystal displays (FMLCD) cell structure 1000 comprises electrodes 1002,1004, their respective substrates 1006, 1008 and index match boundaries1010, 1012 and a liquid crystal formulation 1014 (CLC) sandwichedtherebetween. In a preferred embodiment, the electrodes 1002, 1004 arepatterned into conductive matrices which define pixel, or sub-pixel,locations and provide drive voltage paths for the pixel, or sub-pixel,locations. By applying a voltage across the electrodes associated with aportion of the display, that portion is selectively driven (e.g., bydrive circuitry) to an “on” or “off” state. An exemplary preferred FMLCDcell structure 1000 is intrinsic reflective (front-lit) and includes ananti-reflective coating 1016 on the substrate 1006 (substantiallytransparent) and a black coating 1018 on the substrate 1008 as shown. Itshould be understood, however, that the principles of the presentinvention are also applicable to back-lit LCDs.

FIGS. 11-13 illustrate back and front panel processing and panel matingaccording to the present invention. An incoming back panel (conductivefilm) 1100 (FIG. 11A) is laser etched to create conductive columns 1102(FIG. 11B). Next, polyimide 1104 (FIG. 11C) is printed over theconductive columns 1102 and dried. After this processing step, spacers1106 (FIG. 11D) are sprayed over the entire area of the back panel 1100.Front panel processing is similar. An incoming front panel (conductivefilm) 1200 (FIG. 12A) is laser etched to create conductive rows 1202(FIG. 12B). Next, polyimide 1204 (FIG. 12C) is printed over theconductive rows 1202 and dried. After this processing step, a seal ring1206 (FIG. 12D) is printed around the conductive rows 1202 as shown.Referring to FIG. 13A, the mated and sealed panels 1100, 1200 are filledwith LC to form an LCD cell structure 1300. After the mated panels 1100,1200 are filled with LC, an end seal epoxy 1302 (FIG. 13B) is applied tothe opening in the seal ring 1206 and cured. Additional processing stepsinclude printing black on the back of the panel 1100, 1200, assemblingto driver and electronics, etc. In an alternative embodiment, the backpanel 1100 is provided with conductive rows and the front panel 1200 isprovided with conductive columns. In an alternative embodiment, the backpanel 1100 is provided with a seal ring and the front panel 1200 isprovided with spacers. Of course, electrode patterns other than thoseillustrated can also be provided.

FIG. 14 is a schematic of an ablation system 1400. An exemplarypreferred ablation system 1400 comprises an excimer laser projectionsystem which provides high-speed, high-precision etching ofconductor/substrate structures with plastic substrates, in an etchingprocess suitable for roll-to-roll production. The illustrated ablationsystem 1400 comprises an excimer laser 1402, collimating optics 1404,mask 1406, refractive element 1408, reflective element 1410, substratestage 1412 and mirrors 1414, 1416, 1418 configured as shown. By way ofexample, the ablation system 1400 is similar to a Tamarack ScientificCo. Inc. (Corona, Calif.) Series 300 “Projection UV Exposure System”with the UV lamp replaced by a XeCl excimer laser (308 nm). Thecollimating optics 1404 parallel the beam reflected by the mirror 1414.The mask 1406, by way of example, comprises a dielectric material,aluminum, chrome or quartz. For high fluences (above about 400 mJ/cm²)adielectric mask can be used. For fluences in the midlevel range of 40 to400 mJ/cm², an aluminum mask (minimum line gap 5 μm) can be used. Forlower fluences (e.g., <35 mJ/cm²), a chrome mask can be used. In apreferred embodiment, the mask 1406 is positioned over but does nottouch the film being ablated. An exemplary preferred ablation system1400 employs a Dyson-type lens and a vertically oriented substrate stage1412.

The ablation system 1400 is configured such that the mask 1406 isentirely or partially exposed to a broadened laser beam, which is thensent to the film surface. The complete pattern is therefore ablated onthe ITO very quickly (e.g., at 200 Hz, the time needed to ablate acomplete pattern was ˜1 second) in comparison with the non-masked directlaser beam of prior systems—for which it is critical to preciselycontrol the depth of focus and spot size of the laser, across thesubstrate, as well as the ablation speed. Depending upon the specificprocess, it may be necessary to employ a forced gas (e.g., nitrogenpurge) and vacuum system when ablating and a water-plasma treatmentthereafter in order to remove unwanted particles.

According to an exemplary preferred method of the present invention, theexpanded beam of an excimer laser is projected through a (pre-patterned)mask onto the film conductive layer. The excimer laser 1402 ispreferably controlled in consideration of the material from which themask 1408 is fabricated. The laser control parameters may also need tobe adjusted depending upon the nature of the pattern being etched.

The typical plastic substrate, as compared to glass, has a surfacetopology with point-to-point variations both on a local scale and over alarger area. Surface variations on the order of several μm are common.Layers formed over the plastic substrate (e.g by sputtering ordeposition processes) likewise may have a wavy surface or other surfacevariation. Control of the ablation process according to the presentinvention can, but does not necessarily, take into account these surfacevariations. Generally, the UV irradiation process is controlled to avoidablating the plastic substrate and to leave a protective layer which issufficiently thick to perform its protective function. Thus, in apreferred embodiment, the depth of focus of the laser isselected/controlled to be sufficiently large to take into account theabove-described surface variabilities.

In another preferred embodiment, feedback is employed to adjust thelaser control parameters (e.g., laser power at the surface, pulse width,etc.) to compensate for the above-described surface variations. Anoptical sensor, CCD camera, etc. can be employed to provide a controlinput. Spectroscopy (e.g., elipsometry) can be employed to provideoptical characterizations of the film which reveal changes in itscomposition.

An alternative ablation system is configured to scan in a serpentinepattern with controlled velocity on a first axis and precision steppingon a second axis perpendicular to the first axis. This is conceptuallyillustrated in FIG. 15 where exposure uniformity is achieved over theentire exposure area by scanning with a diamond-shaped homogenized beam,overlapping adjacent scans by 50%, and precisely controlling the scanvelocity.

Although the present invention has been described in terms of thepreferred embodiment above, numerous modifications and/or additions tothe above-described preferred embodiment would be readily apparent toone skilled in the art. It is intended that the scope of the presentinvention extends to all such modifications and/or additions.

We claim:
 1. A method for patterning a multilayered conductor/substratestructure comprising the steps of: providing a multilayeredconductor/substrate structure which includes a plastic substrate and atleast one conductive layer overlying the plastic substrate; andirradiating the multilayered conductor/substrate structure withultraviolet radiation such that portions of the at least one conductivelayer are ablated therefrom; wherein the irradiating step comprisesemploying an excimer laser of a projection-type ablation system toablate portions of the at least one conductive layer by illuminating amask with a collimated laser beam and employing projection opticspositioned between the mask and the at least one conductive layer toproject a pattern from the mask onto the at least one conductive layer.2. The method for patterning a multilayered conductor/substratestructure of claim 1 wherein the ultraviolet radiation is spatiallyincoherent.
 3. The method for patterning a multilayeredconductor/substrate structure of claim 1 wherein the ultravioletradiation has a wavelength in the mid-UV range.
 4. The method forpatterning a multilayered conductor/substrate structure of claim 1wherein the step of employing the excimer laser comprises selecting theexcimer laser depending upon radiation absorption of the at least oneconductive layer at particular wavelengths.
 5. The method for patterninga multilayered conductor/substrate structure of claim 1 wherein thepattern includes a line gap 10 μm or smaller.
 6. The method forpatterning a multilayered conductor/substrate structure of claim 1wherein the steps of providing and irradiating the multilayeredconductor/substrate structure are part of a roll-to-roll productionprocess.
 7. The method for patterning a multilayered conductor/substratestructure of claim 1 wherein the plastic substrate comprises,polyethylenenapthalate (PEN), or polyethersulphofle (PES).
 8. The methodfor patterning a multilayered conductor/substrate structure of claim 1wherein the plastic substrate comprises a polyolefin material.
 9. Themethod for patterning a multilayered conductor/substrate structure ofclaim 1 wherein the at least one conductive layer comprises an oxidelayer.
 10. The method for patterning a multilayered conductor/substratestructure of claim 1 wherein the at least one conductive layer comprisesa metal-based layer.
 11. The method for patterning a multilayeredconductor/substrate structure of claim 1 wherein the at least oneconductive layer comprises a silver-based layer.
 12. The method forpatterning a multilayered conductor/substrate structure of claim 1wherein the at least one conductive layer comprises silver and gold. 13.The method for patterning a multilayered conductor/substrate structureof claim 1 wherein the at least one conductive layer is a multilayeredconductive film.
 14. The method for patterning a multilayeredconductor/substrate structure of claim 1 wherein the at least oneconductive layer, where it has not been etched, has a thickness betweenaround 10 nm and around 120 nm.
 15. The method for patterning amultilayered conductor/substrate structure of claim 1 wherein the atleast one conductive layer has a resistivity of no greater than 80Ω/square.
 16. The method for patterning a multilayeredconductor/substrate structure of claim 1 wherein the at least oneconductive layer has a transmissivity of at least 80%.
 17. The methodfor patterning a multilayered conductor/substrate structure of claim 1wherein the at least one conductive layer comprises an indium tin oxide(ITO) layer.
 18. The method for patterning a multilayeredconductor/substrate structure of claim 17 wherein the ITO layer ispolycrystalline.
 19. The method for patterning a multilayeredconductor/substrate structure of claim 1 wherein the at least oneconductive layer comprises an alloy.
 20. The method for patterning amultilayered conductor/substrate structure of claim 19 wherein the alloyis an indium tin oxide (ITO) alloy.
 21. The method for patterning amultilayered conductor/substrate structure of claim 1 wherein theexcimer laser is selected to emit light at a discrete characteristicwavelength.
 22. The method for patterning a multilayeredconductor/substrate structure of claim 21 wherein the characteristicwavelength is 308 nm.
 23. The method for patterning a multilayeredconductor/substrate structure of claim 21 wherein the characteristicwavelength is 248 nm.
 24. The method for patterning a multilayeredconductor/substrate structure of claim 1 wherein the multilayeredconductor/substrate structure further comprises at least one functionallayer intermediate the at least one conductive layer and the plasticsubstrate, the at least one functional layer comprising an insulatingmaterial.
 25. The method for patterning a multilayeredconductor/substrate structure of claim 24 wherein the irradiating stepcomprises employing and controlling an excimer laser to ablate portionsof the at least one conductive layer without completely decomposing theat least one functional layer therebeneath.
 26. The method forpatterning a multilayered conductor/substrate structure of claim 24wherein the at least one functional layer comprises a layer of actylicwhich abuts the at least one conductive layer.
 27. The method forpatterning a multilayered conductor/substrate structure of claim 24,further comprising: an additional functional layer abutting a side ofthe plastic substrate that faces away from the at least one conductivelayer, the additional functional layer serving to provide structuralprotection and/or environmental protection for the plastic substrate.28. The method for patterning a multilayered conductor/substratestructure of claim 24 wherein the irradiating step comprises employingand controlling the excimer laser to irradiate a portion of the at leastone conductive layer such that a portion of the at least one functionallayer therebeneath heats via thermal conduction through the at least oneconductive layer and swells to assist in ablating the portion of the atleast one conductive layer.
 29. The method for patterning a multilayeredconductor/substrate structure of claim 28 wherein the step ofcontrolling the excimer laser comprises controlling a fluence.
 30. Themethod for patterning a multilayered conductor/substrate structure ofclaim 24 wherein the at least one functional layer comprises aprotective layer which serves to protect layers beneath the protectivelayer from laser irradiation.
 31. The method for patterning amultilayered conductor/substrate structure of claim 30 wherein thelayers beneath comprise a barrier layer which serves to protect theplastic substrate from environmental damage.
 32. The method forpatterning a multilayered conductor/substrate structure of claim 30wherein the layers beneath include the plastic substrate.
 33. The methodfor patterning a multilayered conductor/substrate structure of claim 24wherein the at least one functional layer ocmprises a barrier layerwhich serves to protect the plastic substrate from enviornmental damage.34. The method for patterning a multilayered conductor/substratestructure of claim 33 wherein the barrier layer is inorganic.
 35. Themethod for patterning a multilayered conductor/substrate structure ofclaim 33 wherein the barrier layer has an oxygen transmission rate (OTR)no greater than 0.05 cc/m²/day.
 36. The method for patterning amultilayered conductor/substrate structure of claim 33 wherein thebarrier layer has a water vapor transmission rate (WVTR) no greater than0.05 g/m²/day.
 37. The method for patterning a multilayeredconductor/substrate structure of claim 24, further comprising: anadditional functional layer abutting a side of the plastic substratethat faces away from the at least one conductive layer, the additionalfunctional layer serving to provide structural protection and/orenvironmental protection for the plastic substrate.